1. Field of the Invention
The present invention relates to a lens barrel and a camera, and, more specifically, the invention relates to a lens barrel having a barrier mechanism for moving to a closed position and an open position. In the closed position, the front face of a photographic lens is covered with a barrier, and, in the open position, the front face of the photographic lens is exposed.
2. Description of the Related Art
A known pair of lens barrier blades for a camera is disposed inside a photographic lens barrel (hereinafter referred to as a ‘lens barrel’) in the front portion of the camera. When a photograph is not being taken, the barrier blades are in a closed position in which the barrier blades cover the front portion of the photographic lens. When a photograph is being taken, the barrier blades move to an open position in which the barrier blades are moved away from the front of the photographic lens to allow a luminous flux to enter the photographic lens. Various known driving mechanisms for opening and closing the barrier blades are proposed.
For example, Japanese Patent Application Laid-Open No. 7-159855 discloses a mechanism for opening and closing barrier blades in which the barrier blades are opened and closed by rotating a barrier opening/closing ring, disposed on the distal end portion of the lens barrel, around an optical axis.
More specifically, a cam plate having a cam surface at its distal end is disposed inside a camera body including the lens barrel, wherein the cam plate extends into the lens barrel when the lens barrel is retracted to the camera. Arms extending into the lens barrel are provided on the barrier opening/closing ring. In this barrier opening and closing mechanism, the barrier blades move to the closed position when the lens barrel is retracted to the camera body and the barrier opening/closing ring rotates around the optical axis as the tip of the arms engage with the cam plate.
Another mechanism for opening and closing barrier blades is disclosed in Japanese Patent Application Laid-Open No. 7-20369. In this mechanism for opening and closing the barrier blades, a barrier driving ring rotatable around an optical axis is disposed at the front portion of a lens barrel. This barrier driving ring is, for example, rotated around the optical axis by, for example, a motor driving mechanism.
More specifically, at the distal end of the lens barrel, the barrier driving ring and a barrier driving gear with one end extending into the lens barrel are disposed. Inside the lens barrel, the motor driving mechanism is disposed. In such a mechanism for opening and closing a barrier, the barrier blades are opened and closed by rotating the barrier driving ring. To rotate the barrier driving ring, the barrier driving ring is connected to the barrier driving gear and then the barrier driving gear is connected to the motor driving mechanism.